class FastMmapedFile

VALUE method_to_metrics(VALUE UNUSED(self), VALUE file_list) {
    struct hashmap map;
    hashmap_setup(&map);

    if (!aggregate_files(&map, file_list)) {  // all entries in map are now copies that need to be disposed
        hashmap_destroy(&map);
        raise_last_exception();
        return Qnil;
    }

    entry_t **sorted_entries;

    if (!sort_map_entries(&map, &sorted_entries)) {
        hashmap_destroy(&map);

        raise_last_exception();
        return Qnil;
    }

    VALUE rv = rb_str_new("", 0);
    if (!entries_to_string(rv, sorted_entries, hashmap_size(&map))) {
        free(sorted_entries);
        hashmap_destroy(&map);

        raise_last_exception();
        return Qnil;
    }

    RB_GC_GUARD(file_list);  // ensure file list is not GCed before this point
    free(sorted_entries);
    hashmap_destroy(&map);
    return rv;
}